CN110999507B

CN110999507B - Channel reservation signal in NR shared spectrum

Info

Publication number: CN110999507B
Application number: CN201880051215.2A
Authority: CN
Inventors: J·雷; J·孙; T·卡多斯
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2017-08-08
Filing date: 2018-08-03
Publication date: 2023-09-12
Anticipated expiration: 2038-08-03
Also published as: WO2019032402A1; CN110999507A; US10687356B2; US20190053269A1; EP3666027A1

Abstract

Methods, systems, and devices for wireless communications are described. The transmitting device may obtain channel access after a Clear Channel Assessment (CCA) operation. The transmitting device may then determine an offset between the boundary of the symbol and the particular time at which channel access was obtained. The transmitting device may generate a Channel Reservation (CR) preamble based on the offset and transmit the CR preamble. The transmitting device may also generate a CR preamble based on occupancy of a subband or beam used by the transmitting device. The receiver device may monitor for a CR message based on the CR preamble.

Description

Channel reservation signal in NR shared spectrum

Priority claim according to 35 U.S. C. ≡119

This patent application claims priority from provisional application No.62/542,560 entitled "CHANNEL RESERVATION SIGNAL IN NR SHARED SPECTRUM (channel reservation signal in NR shared SPECTRUM)" filed 8, 2017, and non-provisional application No.16/053,154 entitled "CHANNEL RESERVATION SIGNAL IN NR SHARED SPECTRUM (channel reservation signal in NR shared SPECTRUM)" filed 8, 2018, which are assigned to the assignee of the present application and hereby expressly incorporated herein by reference.

Background

Aspects of the present disclosure relate generally to wireless communication systems and channel reservation procedures.

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Such networks, which are typically multiple-access networks, support communication for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). UTRAN is a Radio Access Network (RAN) defined as part of a Universal Mobile Telecommunications System (UMTS), which is a third generation (3G) mobile telephony technology supported by the third generation partnership project (3 GPP). Examples of multiple-access network formats include Code Division Multiple Access (CDMA) networks, time Division Multiple Access (TDMA) networks, frequency Division Multiple Access (FDMA) networks, orthogonal FDMA (OFDMA) networks, and single carrier FDMA (SC-FDMA) networks.

A wireless communication network may include several base stations or node bs capable of supporting several User Equipment (UE) communications. The UE may communicate with the base station via the downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.

SUMMARY

A wireless device may gain access to a communication channel or medium after a Clear Channel Assessment (CCA) operation. The wireless device may determine a timing gap or offset between a boundary of an Orthogonal Frequency Division Multiplexing (OFDM) symbol and a particular time to obtain channel access. The wireless device may then generate a Channel Reservation (CR) preamble based on the offset and transmit the CR preamble. The length of the CR preamble may be adaptive such that subsequent CR messages are aligned with the symbol timing. The CR signal including the CR preamble and the CR message may be adaptive based on other factors, such as occupancy of a particular subband or beam used by the wireless device.

A method of wireless communication is described. The method may include: obtaining channel access after a Clear Channel Assessment (CCA) operation; determining an offset between a boundary of the symbol and a specific time at which channel access is obtained; generating a Channel Reservation (CR) preamble based on the offset; the CR preamble is transmitted.

A method of wireless communication is described. The method may include: obtaining channel access to a communication channel after a Clear Channel Assessment (CCA) operation, wherein the communication channel comprises a plurality of subbands; at least one Channel Reservation (CR) signal is generated based on the plurality of subbands, and the at least one CR signal is transmitted.

A method of wireless communication is described. The method may include: obtaining channel access after a Clear Channel Assessment (CCA) operation; generating at least one Channel Reservation (CR) signal based on availability of beams in a plurality of possible directions; and transmitting the at least one CR signal using one beam in a specific direction among the plurality of possible directions.

A method of wireless communication is described. The method may include: receiving a signal; determining that the signal includes a Channel Reservation (CR) preamble; monitoring a symbol for a CR message, wherein the symbol follows an end point of the CR preamble; and identifying channel occupancy information based on the CR message.

An apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory, which when executed by the processor, are operable to cause the apparatus to: obtaining channel access after a Clear Channel Assessment (CCA) operation; determining an offset between a boundary of the symbol and a specific time at which channel access is obtained; generating a Channel Reservation (CR) preamble based on the offset; the CR preamble is transmitted.

A non-transitory computer-readable medium storing code for wireless communication is described. The code may include instructions executable to: obtaining channel access after a Clear Channel Assessment (CCA) operation; determining an offset between a boundary of the symbol and a specific time at which channel access is obtained; generating a Channel Reservation (CR) preamble based on the offset; the CR preamble is transmitted.

An apparatus for wireless communication is described. The apparatus may include: means for obtaining channel access after a Clear Channel Assessment (CCA) operation; means for determining an offset between a boundary of the symbol and a particular time at which channel access is obtained; means for generating a Channel Reservation (CR) preamble based on the offset; and means for transmitting the CR preamble.

In some examples of the methods, apparatus, or non-transitory computer-readable media described herein, generating the CR preamble includes dividing the CR preamble into a plurality of segments, each segment including a different waveform. In some cases, the plurality of segments includes a first segment having a fixed duration, a second segment having a variable duration, and a third segment having a fixed duration. In some cases, a variable duration of the second segment is determined such that a total duration of the CR preamble is aligned with a duration of the offset.

In some cases, generating the CR preamble further comprises: applying a different correlation type to each segment may include applying an autocorrelation type to the first segment and a cross-correlation type to the third segment. In some cases, the CR preamble comprises a dual layer waveform construction, and wherein generating the CR preamble comprises: a short spreading sequence is used for the first layer of the CR preamble and a code cover sequence is used for the second layer of the CR preamble. In some cases, generating the CR preamble includes: a cross product operation of the code cover sequence indicated by the length L vector and the spreading sequence indicated by the length K vector is performed. In some cases, the offset has a duration that is shorter than a duration of the CR preamble.

Some examples of the methods, apparatus, or non-transitory computer-readable media described herein may further include processes, features, devices, or instructions for: truncating the CR preamble such that the CR preamble has a start point aligned with a specific time and an end point aligned with a boundary of a symbol, or aligning the end point of the CR preamble with a boundary of a next symbol after the symbol and adding a padding signal between the specific time and the start of the CR preamble. In some cases, the offset has a duration that is longer than the duration of the CR preamble. Some examples of the methods, apparatus, or non-transitory computer-readable media described herein may further include processes, features, devices, or instructions for: at least one padding sample is added in a gap between the end of the CR preamble and the boundary of the symbol. In some cases, the at least one fill sample includes at least one of: a copy of at least one sample from the beginning of the CR preamble, a copy of at least one sample from the end of a CR message scheduled for transmission in a next symbol after the symbol, or a PN-like signal.

In some examples of the methods, apparatus, or non-transitory computer-readable media described herein, the at least one CR signal includes a CR preamble and a CR message in a symbol after an end point of the CR preamble. In some cases, generating the at least one CR signal includes: a separate CR message is generated for each of the plurality of subbands. In some cases, the payload of each CR message indicates occupancy of a particular sub-band on which each CR message is transmitted. In some cases, generating the at least one CR signal includes: at least one CR message indicating occupancy of more than one of the plurality of subbands is generated. In some cases, the payload of the at least one CR message includes a bitmap indicating occupancy of a particular sub-band of the plurality of sub-bands.

In some examples of the methods, apparatus, or non-transitory computer-readable media described herein, the at least one CR signal includes a CR message indicating occupancy information for at least one other beam having a direction different from the particular direction.

In some examples of the methods, apparatus, or non-transitory computer-readable media described herein, the signal includes three segments, each segment including a different waveform. In some cases, determining that the signal includes a CR preamble includes: a switching point of a waveform of a first segment of the signal is identified. In some cases, the end point of the CR preamble is determined based on the switch point of the waveform of the final segment of the signal. In some cases, the signal comprises a dual layer waveform, wherein the first layer comprises a short spreading sequence and the second layer comprises a code coverage sequence. In some cases, the end point of the CR preamble is determined based on detecting a particular sample associated with the dual layer waveform. In some cases, the channel occupancy information indicates occupancy of a particular sub-band on which the CR message is received. In some cases, the channel occupancy information indicates occupancy of at least one other sub-band different from the sub-band on which the CR message was received. In some cases, the CR message is received on a beam in a particular direction among a plurality of possible directions. In some cases, the channel occupancy information indicates occupancy of at least one other beam having a direction different from the particular direction.

The foregoing has outlined rather broadly the features and technical advantages of examples in accordance with the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The features of the concepts disclosed herein, both as to their organization and method of operation, together with associated advantages, will be better understood from the following description when considered in connection with the accompanying drawings. Each of the figures is provided for the purpose of illustration and description and is not intended to limit the claims.

Brief Description of Drawings

A further understanding of the nature and advantages of the present disclosure may be obtained by reference to the following drawings. In the drawings, similar components or features may have the same reference numerals. Further, individual components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference number is used in the specification, the description may be applied to any one of the similar components having the same first reference number regardless of the second reference number.

Fig. 1 is a block diagram illustrating details of a wireless communication system.

Fig. 2 is a block diagram illustrating a design of a base station/eNB and a UE configured in accordance with an aspect of the present disclosure.

Fig. 3 illustrates an example of an adaptive Channel Reservation (CR) preamble.

Fig. 4 illustrates an example configuration of an adaptive CR signal based on medium access timing.

Fig. 5 illustrates an example configuration of an adaptive CR signal based on medium access timing.

Fig. 6 illustrates an example configuration of an adaptive CR signal based on medium access timing.

Fig. 7 illustrates an example configuration of an adaptive CR signal based on subband occupation.

Fig. 8 illustrates an example configuration of adaptive CR signals based on beam direction availability.

Fig. 9 illustrates an example process flow in a system supporting adaptive CR signaling techniques.

Fig. 10 illustrates a method for transmission of adaptive CR signaling in accordance with aspects of the present disclosure.

Fig. 11 illustrates a method for transmission of adaptive CR signaling in accordance with aspects of the present disclosure.

Fig. 12 illustrates a method for transmission of adaptive CR signaling in accordance with aspects of the present disclosure.

Fig. 13 illustrates a method of reception and processing of adaptive CR signaling in accordance with aspects of the present disclosure.

Detailed Description

In wireless communications in a dedicated or licensed communication medium, devices may be scheduled for data transmission using specific time slots and resources. However, in unlicensed or shared communication media, the radio spectrum may be available for use by different radio access technologies or by multiple mobile network operators. Thus, devices may need to contend for medium access using various mechanisms. For example, before a device can begin transmitting on an unlicensed communication medium, it may need to determine whether another device is already occupying the medium (i.e., whether signals from other devices have been transmitted on the medium). In some cases, the device may perform energy detection by continually listening to the medium for any active Radio Frequency (RF) energy. If the measured RF energy exceeds a certain threshold, the medium is deemed busy and the device will refrain from transmitting during periods when the medium is busy in order to avoid collisions. In some examples, the device may detect a particular signal in order to determine occupancy of the medium. For example, a device may detect a preamble of a transmission from another device to determine if the other device intends to occupy the medium for some amount of time.

Such mechanisms for avoiding collisions may be classified as a "listen before talk" (LBT) procedure in that a device listens to a medium to determine if the medium is busy before the device transmits on the medium. The LBT procedure may be performed by a User Equipment (UE) or a base station for medium access. Among the various LBT procedures used, preamble detection may be more efficient than energy detection for indicating channel occupancy and avoiding collisions. In particular, the medium occupation time can also be signaled with a preamble, which allows other devices to determine how long the medium will be occupied and avoids unnecessary random access by aggressor devices.

A combination of energy detection and preamble detection may also be used. In some examples, a Clear Channel Assessment (CCA) procedure is performed prior to transmission over the communication medium, where the CCA procedure may include aspects of both energy detection and preamble detection. Thus, once a transmitting device obtains channel access after a successful CCA procedure, it may transmit its own preamble to inform other devices that it intends to occupy the medium for some amount of time and allow other devices to perform their own CCA procedure and detect the signal (i.e., preamble). In particular, the preamble transmitted by the transmitting device may be part of a Channel Reservation (CR) signal, which may include at least a CR preamble and a CR message. As used herein, a successful CCA procedure or CCA clear may include the result of a procedure performed by a wireless device that determines that the communication medium is not deemed occupied by communications from other devices (e.g., via energy detection and/or preamble detection) and is available for communications by the wireless device.

The CR preamble may indicate to other devices (such as potential aggressors) that a CR message is forthcoming. The transmitting device may send a CR preamble after completion of a CCA procedure indicating an available communication medium and then a CR message after the CR preamble, wherein the CR message may include a Network Allocation Vector (NAV), a packet length, and/or beam training information. In some instances, the NAV indicates the duration of the channel occupancy time of the transmitting device and informs other devices that they should defer from accessing the medium for a length of time. In some implementations, a transmitting device may reuse a Physical Downlink Control Channel (PDCCH) and demodulation reference signal (DMRS) format for CR messages to maximize interoperability between licensed and unlicensed designs.

In some examples, a cellular communication system may use a transmission timeline including Orthogonal Frequency Division Multiplexing (OFDM) symbols according to a fixed pattern. In particular, long Term Evolution (LTE) and 5G New Radio (NR) systems may divide time resources into equally spaced symbols for scheduling resources and synchronizing transmissions between devices within a network. However, in unlicensed spectrum, a device performs a channel contention procedure before gaining medium access, and medium access may be obtained at any time (including between symbol boundaries). In some examples, LTE or NR devices may compete for medium access with non-cellular devices (such as WLAN devices that do not operate under a similar time-divided symbol timeline). Thus, a cellular device may obtain medium access (e.g., a successful CCA procedure) at any time, but its transmissions (including CR message transmissions) may still need to follow a particular transmission timeline according to system parameters.

To improve reliable and power-efficient CR signal detection, a transmitting device may adapt its CR signal transmission to account for gaps between medium access timing (i.e., CCA clear) and ODFM symbol boundaries according to system timing, differences between the system bandwidth of the transmitting device and the system bandwidth of potential aggressors, or differences in channel occupancy across different sub-bands and/or beam directions. In particular, the techniques and apparatuses described herein provide for adaptive transmission of CR signals in unlicensed or shared spectrum. For example, a transmitting device may adapt a CR preamble based on an offset (i.e., a gap) between a time when channel access is obtained by the transmitting device and a subsequent symbol boundary. Adaptive generation of the CR preamble may allow for subsequent CR messages to be transmitted according to predefined system timing and for other devices to identify a particular symbol for which the CR message is intended. Further, in instances where the bandwidth may be further divided into subbands and the occupancy duration of the device may be different across different subbands, the CR message may be adapted to indicate information regarding occupancy of the plurality of subbands. In other examples where the device may transmit beams in different directions, the CR message may be adapted to indicate information about occupancy of different beams.

The detailed description set forth below in connection with the appended drawings and the accompanying drawings is intended as a description of various configurations and is not intended to limit the scope of the present disclosure. Rather, the detailed description includes specific details for the purpose of providing a thorough understanding of the subject matter of the present invention. It will be apparent to one skilled in the art that these specific details are not required in every case and that, in some instances, well-known structures and components are shown in block diagram form for clarity of presentation.

The present disclosure relates generally to providing or participating in authorized shared access between two or more wireless communication systems (also referred to as wireless communication networks). In various embodiments, the techniques and apparatuses may be used for wireless communication networks such as Code Division Multiple Access (CDMA) networks, time Division Multiple Access (TDMA) networks, frequency Division Multiple Access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, and other communication networks. As described herein, the terms "network" and "system" may be used interchangeably.

OFDMA networks may implement radio technologies such as evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM, and the like. UTRA, E-UTRA and global system for mobile communications (GSM) are parts of Universal Mobile Telecommunications System (UMTS). Specifically, long Term Evolution (LTE) is a version of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in literature from an organization named "third generation partnership project" (3 GPP), while cdma2000 is described in literature from an organization named "third generation partnership project 2" (3 GPP 2). These various radio technologies and standards are known or under development. For example, the third generation partnership project (3 GPP) is a collaboration between telecommunications associations, which is intended to define the globally applicable third generation (3G) mobile phone specifications. The 3GPP Long Term Evolution (LTE) is a 3GPP project aimed at improving the Universal Mobile Telecommunications System (UMTS) mobile telephony standard. The 3GPP may define specifications for next generation mobile networks, mobile systems, and mobile devices. The present disclosure focuses on evolution from LTE, 4G, 5G and beyond wireless technologies with shared access to the wireless spectrum between networks using new and different radio access technologies or sets of radio air interfaces.

In particular, 5G networks contemplate various deployments, various spectrum, and various services and devices that may be implemented using an OFDM-based unified air interface. To achieve these goals, further enhancements to LTE and LTE-a are considered in addition to the development of New Radio (NR) technologies. The 5G NR will be scalable to provide coverage for: (1) Having ultra-high density (e.g., -1M node/km) ² ) Ultra-low complexity (e.g., -tens of bits/second), ultra-low energy (e.g., -10+ years of battery life), and deep-covered large-scale internet of things (IoT) capable of reaching challenging locations; (2) Including mission critical controls with strong security (to protect sensitive personal, financial, or confidential information), ultra-high reliability (e.g., -99.9999% reliability), ultra-low latency (e.g., -1 ms), and users with a wide range of mobility or lack of mobility; and (3) has enhanced mobile broadband including very high capacity (e.g., -10 Tbps/km) ² ) Extreme data rates (e.g., multiple Gbps rates, 100+mbps user experience rate), and depth awareness with advanced discovery and optimization.

5G NR can be implemented to: using an optimized OFDM-based waveform with a scalable set of parameters and a Transmission Time Interval (TTI); having a common, flexible framework to efficiently multiplex services and features using a dynamic, low latency Time Division Duplex (TDD)/Frequency Division Duplex (FDD) design; and advanced wireless technologies such as massive Multiple Input Multiple Output (MIMO), robust millimeter wave (mmWave) transmission, advanced channel coding, and device-centric mobility. Scalability of parameter sets (and scaling of subcarrier spacing) in 5G NR can efficiently address operating various services across various spectrums and various deployments. For example, in various outdoor and macro coverage deployments with less than 3GHz FDD/TDD implementations, the subcarrier spacing may occur at 15kHz, e.g., over bandwidths of 1, 5, 10, 20MHz, etc. For other various outdoor and small cell coverage deployments of TDD greater than 3GHz, the subcarrier spacing may occur at 30kHz, for example, over 80/100MHz bandwidth. For other various indoor wideband implementations, this subcarrier spacing may occur, for example, at 60kHz over a 160MHz bandwidth by using TDD over the unlicensed portion of the 5GHz band. Finally, for various deployments where mmWave components are used for transmission at 28GHz TDD, subcarrier spacing may occur at 120kHz, for example, over 500MHz bandwidth. Other deployments of different subcarrier spacings over different bandwidths are also within the scope of the present disclosure.

The scalable set of parameters of the 5G NR facilitates scalable TTIs to meet various latency and quality of service (QoS) requirements. For example, shorter TTIs may be used for low latency and high reliability, while longer TTIs may be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs may allow transmissions to begin on symbol boundaries. The 5G NR also contemplates a self-contained integrated subframe design with uplink/downlink scheduling information, data, and acknowledgements in the same subframe. The self-contained integrated subframes support communication in unlicensed or contention-based shared spectrum, supporting adaptive uplink/downlink that can be flexibly configured on a per-cell basis to dynamically switch between uplink and downlink to meet current traffic needs.

Various other aspects and features of the disclosure are described further below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and non-limiting. Based on the teachings herein one skilled in the art will appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or both structures and functionality that is complementary to or different from one or more of the aspects set forth herein. For example, the methods may be implemented as part of a system, apparatus, device, and/or as instructions stored on a computer-readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

Fig. 1 is a block diagram illustrating a network 100 including various base stations and UEs configured in accordance with aspects of the present disclosure. In some examples, network 100 represents, for example, a 5G network. The network 100 includes a number of evolved node bs (enbs) 105 and other network entities. An eNB may be a station that communicates with a UE and may also be referred to as a base station, an access point, a gNB, and the like. Each eNB 105 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a particular geographic coverage area of an eNB and/or an eNB subsystem serving the coverage area, depending on the context in which the term is used.

An eNB may provide communication coverage for a macro cell or small cell (such as a pico cell or femto cell), and/or other types of cells. Macro cells generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription with the network provider. Small cells (such as pico cells) typically cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription with the network provider. A small cell, such as a femto cell, will also typically cover a relatively small geographic area (e.g., a residence) and may provide restricted access for UEs associated with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the residence, etc.) in addition to unrestricted access. An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. In the example shown in fig. 1, enbs 105D and 105e are conventional macro enbs, while enbs 105a-105c are macro enbs enabled with one of 3-dimensional (3D), full-dimensional (FD), or massive MIMO. The enbs 105a-105c utilize their higher dimensional MIMO capabilities to increase coverage and capacity using 3D beamforming in both elevation and azimuth beamforming. The eNB 105f is a small cell eNB, which may be a home node or a portable access point. An eNB may support one or more (e.g., two, three, four, etc.) cells.

The network 100 may support synchronous or asynchronous operation. For synchronous operation, the enbs may have similar frame timing and transmissions from different enbs may be approximately aligned in time. For asynchronous operation, the enbs may have different frame timing and transmissions from different enbs may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100 and each UE may be stationary or mobile. A UE may also be called a terminal, mobile station, subscriber unit, station, etc. The UE may be a cellular telephone, a Personal Digital Assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless telephone, a Wireless Local Loop (WLL) station, etc. UEs 115a-115d are examples of mobile smart phone type devices that access network 100. The UE may also be a machine specifically configured for connected communications, including Machine Type Communications (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT), etc. UEs 115e-115k are examples of various machines configured for communication with access network 100. The UE may be capable of communicating with any type of eNB (macro eNB, small cell, etc.). In fig. 1, a lightning beam (e.g., a communication link) indicates a wireless transmission between a UE and a serving eNB, which is an eNB designated to serve the UE on the downlink and/or uplink, or a desired transmission between enbs, and a backhaul transmission between enbs.

The communication links depicted in fig. 1 may include licensed, unlicensed, or communication links in a shared Radio Frequency (RF) spectrum. In some examples, a shared spectrum may refer to a light licensed spectrum and/or a spectrum in which there may be some level of coordination between communications of different Radio Access Technologies (RATs) or some level of preference given to communications of a particular RAT, such as, for example, an incumbent RAT. In other examples, a shared spectrum may generally refer to a spectrum in which different RATs coexist or operate within the same RF spectrum band, which may include a licensed/coordinated spectrum, or alternatively, a fully unlicensed spectrum in which different RATs may freely contend for access to a channel medium using various channel contention techniques. Aspects described in this disclosure may be applicable to various shared or unlicensed spectrum schemes. Accordingly, the terms shared spectrum and unlicensed spectrum are used interchangeably herein unless otherwise indicated.

In operation of network 100, enbs 105a-105c serve UEs 115a and 115b using 3D beamforming and coordinated spatial techniques such as coordinated multipoint (CoMP) or multi-connectivity. Macro eNB 105d performs backhaul communications with enbs 105a-105c and small cell eNB 105 f. Macro eNB 105d also transmits multicast services subscribed to and received by UEs 115c and 115 d. Such multicast services may include mobile televisions or streaming video, or may include other services for providing community information (such as weather emergencies or alerts, such as amber alerts or gray alerts).

The network 100 also supports mission-critical communications with ultra-reliable and redundant links for mission-critical devices, such as the UE 115e, which in the example depicted in fig. 1 is a drone. The redundant communication links with UE 115e include those from macro enbs 105d and 105e, as well as small cell eNB 105f. Other machine type devices, such as UE 115f (thermometer), UE 115g (smart meter), and UE 115h (wearable device), may communicate directly with base stations, such as small cell eNB 105f and macro eNB 105e, through network 100, or in a multi-hop configuration by communicating with another user device relaying its information to the network, such as UE 115f communicating temperature measurement information to smart meter UE 115g, which is then reported to the network through small cell eNB 105f. Network 100 may also provide additional network efficiency through dynamic, low latency TDD/FDD communications, such as in a vehicle-to-vehicle (V2V) mesh network between UEs 115i-115k communicating with macro eNB 105 e.

In a shared spectrum configuration, wireless devices (such as base station 105 and UE 115) may need to determine that the medium is clear before transmitting on the shared medium. Once channel access has been obtained, the wireless device may also transmit a channel reservation signal to other devices and potential aggressors that the channel has been reserved for a particular duration. Due to the contention nature of the shared spectrum and coexistence with various types of RATs, the base station 105 or UE 115 may obtain channel access between OFDM symbol boundaries. Thus, the base station 105 or the UE 115 may use an adaptive Channel Reservation (CR) preamble based on an offset between a time when channel access is obtained and an OFDM symbol boundary according to system timing. The adaptive CR preamble may indicate to other devices (e.g., potential aggressors) that a CR message is forthcoming and allow transmission of the CR message to align with OFDM symbol boundaries. The CR signal including the CR preamble and the CR message may also be adapted based on the subbands or directional beams used for transmission by the base station 105 or UE 115, as will be described in further detail herein.

The techniques described herein relate to the transmission of CR signals by a wireless device before the wireless device is intended to transmit further signals. Thus, a wireless device transmitting a CR signal may be referred to in this disclosure as a "transmitting device," which may be any wireless device, including a base station 105 or a UE 115.

Fig. 2 shows a block diagram of the design of base station/eNB 105 and UE 115, which may be one of the base stations/enbs and one of the UEs in fig. 1. At the eNB 105, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be used for various control channels, such as PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH, etc. The data may be used for PDSCH and the like. Transmit processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols (e.g., for PSS, SSS, and cell-specific reference signals). A Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to Modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a through 232t may be transmitted via antennas 234a through 234t, respectively.

At the UE 115, antennas 252a through 252r may receive the downlink signals from the eNB 105 and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 may obtain received symbols from all demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 115 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive and process data (e.g., for PUSCH) from a data source 262 and control information (e.g., for PUCCH) from a controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for SC-FDM, etc.), and transmitted to the eNB 105. At the eNB 105, the uplink signals from the UE 115 may be received by the antennas 234, processed by the demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 115. Processor 238 may provide the decoded data to data sink 239 and the decoded control information to controller/processor 240.

Controllers/processors 240 and 280 may direct the operation at eNB 105 and UE 115, respectively. The controller/processor 240 and/or other processors and modules at the eNB 105 may perform or direct the execution of the functional blocks illustrated in fig. 10-13, and/or other various processes for the techniques described herein. The controller/processor 280 and/or other processors and modules at the UE 115 may also perform or direct the execution of the functional blocks illustrated in fig. 10-13, and/or other processes for the techniques described herein. Memories 242 and 282 may store data and program codes for eNB 105 and UE 115, respectively. For example, memory 242 may store instructions that, when executed by processor 240 or other processor depicted in fig. 2, cause base station 105 to perform the operations described with respect to fig. 10-13. Similarly, the memory 282 may store instructions that, when executed by the processor 280 or other processor depicted in fig. 2, cause the UE 115 to perform the operations described with respect to fig. 10-13. The scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Although illustrated in fig. 2 as distinct components, the functionality described above with respect to the blocks may be implemented in hardware, software, or a combination of components or various combinations of components. For example, the functions described with respect to transmit processor 220, receive processor 238, or TX MIMO processor 230 may be performed by processor 240 or under the control of processor 240.

Wireless communication systems operated by different network operating entities (e.g., network operators) may share spectrum. In some examples, the network operating entity may be configured to: the entire designated shared spectrum is used for at least a period of time before another network operating entity uses the entire designated shared spectrum for a different period of time. Thus, in order to allow network operating entities to use a complete designated shared spectrum, and to mitigate interfering communications between different network operating entities, certain resources (e.g., time) may be partitioned and allocated to different network operating entities for a particular type of communication.

For example, a network operating entity may be allocated specific time resources reserved for exclusive communication over the entire shared spectrum by the network operating entity. Other time resources may also be allocated to a network operating entity that communicates using the shared spectrum in preference to other network operating entities. These time resources that are preferentially used by network operating entities may be utilized by other network operating entities on an opportunistic basis without the prioritized network operating entities utilizing these resources. Any network operator may be allocated additional time resources to be used on an opportunistic basis.

Arbitration of access to the shared spectrum and time resources between different network operating entities may be controlled centrally by separate entities, determined autonomously by a predefined arbitration scheme, or determined dynamically based on interactions between wireless nodes of the network operator.

In some cases, the UE 115 and the base station 105 may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed (e.g., contention-based) spectrum. In the unlicensed frequency portion of the shared radio frequency spectrum band, the UE 115 or the base station 105 may conventionally perform a medium listening procedure to contend for access to the spectrum. For example, the UE 115 or the base station 105 may perform a Listen Before Talk (LBT) procedure, such as Clear Channel Assessment (CCA), prior to communication to determine whether a shared channel is available. The CCA may include an energy detection procedure to determine whether there are any other active transmissions. For example, the device may infer that a change in the Received Signal Strength Indicator (RSSI) of the power meter indicates that the channel is occupied. In particular, signal power concentrated in a certain bandwidth and exceeding a predetermined noise floor may be indicative of another wireless transmitter. CCA may also include detection of a particular sequence indicating channel usage. For example, another device may transmit a particular preamble prior to transmitting the data sequence. In some cases, the LBT procedure may include the wireless node as a proxy for the collision, which adjusts its own backoff window based on the amount of energy detected on the channel and/or acknowledgement/negative acknowledgement (ACK/NACK) feedback for the packet it transmits.

Using a media sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiency. This may be particularly apparent when multiple network operating entities (e.g., network operators) attempt to access a shared resource. In 5G network 100, base station 105 and UE 115 may be operated by the same or different network operating entities. In some examples, an individual base station 105 or UE 115 may be operated by more than one network operating entity. In other examples, each base station 105 and UE 115 may be operated by a single network operating entity. The requirement that each base station 105 and UE 115 of different network operating entities contend for shared resources may result in inefficient communication, especially if the channel contention procedure involves only energy detection.

In some examples, the wireless device may send a Channel Reservation (CR) signal including a CR preamble and a CR message to indicate to a potential attacker that the transmitting device will occupy the shared spectrum for a particular amount of time. Before a transmitting device sends a CR signal, it may first need a clear CCA procedure to gain access to the shared spectrum. However, the time at which the transmitting device clears the CCA procedure may not be aligned with the OFDM symbol boundary of the system in which the transmitting device is operating, while the transmitting device may still need to transmit the CR message according to the system timing. Thus, the transmitting device may use an adaptive CR signal that uses the potential offset between the time it obtained access to the shared spectrum and the OFDM symbol boundary.

Fig. 3 illustrates an example in which a transmitting device (such as base station 105 or UE 115) may adapt a preamble length based on an offset between a CCA procedure-determined time of medium clear (i.e., CCA clear) and an OFDM symbol boundary. For example, as depicted in fig. 3, a transmitting device may obtain channel access at a time 310 that is not aligned with an OFDM symbol boundary. In the illustrated example, the next OFDM symbol boundary occurs at time 320. The transmitting device may generate the CR preamble 300 accordingly such that the length of the CR preamble 300 spans an offset 330 or time gap between time 310 and time 320. In particular, the transmitting device may divide the CR preamble 300 into three segments 340, 350, and 360, wherein the CR preamble 300 includes a different waveform in each segment.

The different waveforms in each segment may have different properties that allow the receiver of the CR preamble 300 to efficiently identify the signal as a CR preamble and monitor for subsequent CR messages at the appropriate time. In some examples, the transmitting device may apply different correlation types or filters such that the CR preamble 300 exhibits different properties in different segments. For example, an autocorrelation type may be applied to the waveform of the first segment 340. As a result, the properties of the CR preamble signal in segment 340 may include a gradual rising edge 370, which may allow the receiver of the CR preamble 300 to detect the presence of the CR preamble 300 on the transmission medium and determine a general starting point of the CR preamble 300.

However, the transmitting device may apply a different correlation type to the CR preamble 300 signal in segment 360. In some examples, the transmitting device may apply a cross-correlation type to the waveform of the third segment 360. Based on the type of cross-correlation applied, the CR preamble 300 waveform in segment 360 may have a sharp peak 380 that may indicate to the receiver of the CR preamble 300 the exact end point of the CR preamble 300 and allow the receiver to identify a particular OFDM symbol boundary that begins monitoring for subsequent CR messages at time 320.

The transmitting device may further apply a different correlation type to the CR preamble 300 signal in the segment 350. The correlation type applied to the segment 350 may be one of a plurality of correlation types and is selected such that at least a minimum signal is transmitted across the medium to indicate the presence of the CR preamble 300. Further, the length of the CR preamble 300 waveform in the segment 350 may be variable, the length of which is adapted based on the offset 330. Thus, while the length of segments 340 and 360 may be fixed or deterministic, the length of segment 350 may vary depending on offset 330 and may have a longer or shorter duration in order to allow the entire CR preamble 300 signal to span the length of offset 330.

Fig. 4 illustrates an example configuration 400 of adaptive CR preamble length based on time of CCA clear procedure completion relative to OFDM symbol timing. In some examples, the CR preamble length may be adapted using the techniques described above with respect to fig. 3. In the illustrated example, the transmitting device may obtain channel access at time 410a during symbol k after completion of the CCA clear procedure. The offset 440a between CCA clear 410a and the subsequently available OFDM symbol boundary 420a may be greater than one symbol length 450a (i.e., the symbol boundary of symbol k may not be considered in this example because CR preamble 460a may require a minimum length of time for proper decoding at the receiver). Thus, the transmitting device may adapt the length of the CR preamble 460a such that it spans the length of time between times 410a and 420 a. Once the CR preamble 460a is transmitted, the transmitting device transmits the CR message 470a in the subsequent symbol at symbol k+2. In an example of the present invention, CR message 470a may span one symbol length between symbol boundaries 420a and 430 a.

In a second example illustrated in fig. 4, the transmitting device may obtain channel access at time 410b during symbol k+1 after completion of the CCA clear procedure. The offset 440b between CCA clear 410b and the subsequently available OFDM symbol boundary 420b may be less than one symbol length 450b. Thus, the transmitting device may adapt the length of the CR preamble 460b such that it spans the length of time between times 410b and 420 b. Once the CR preamble 460b is transmitted, the transmitting device transmits the CR message 470b in the subsequent symbol at symbol k+2. In an example of the present invention, CR message 470b may span one symbol length between symbol boundaries 420b and 430 b.

Other techniques for adaptive CR preamble generation are depicted in fig. 5 and 6. Instead of generating a plurality of segmented CR preambles with different associated attributes, the transmitting device may generate a CR preamble of a particular length. In some implementations, the CR preamble may include a two-layer waveform construction in which a short spreading sequence is used for the first layer and a code coverage sequence is used for the second layer. In the first layer, a short spreading sequence with a time duration T0 is used, the sampling rate of which is fs=k/T0, wherein the spreading sequence is represented by a length K vectorAnd (5) marking. Examples of sequence types that may be used may include CAZAC, pseudo Noise (PN), walsh codes, golay codes, and the like. The second layer may include a code coverage sequence of length L, where LT0 spans an integer number of OFDM symbols. The code covering sequence may be composed of a vector of size L +.>And (5) marking. Preamble waveform samples (P) may be generated by cross-product of spreading code cover B and sequence S, where p=b×s= [ B ] ₁ s ₁ b ₁ s ₂ …b ₁ s _K b ₂ s ₁ b ₂ s ₂ …b ₂ s _K …b _L s ₁ b _L s ₂ …b _L s _K ]。

The dual layer waveform CR preamble may span a fixed length of LK. However, fig. 5 illustrates an example 500 in which the offset between the time at which channel access is obtained and the boundary of a subsequent OFDM symbol is less than the CR preamble length. As depicted in fig. 5, in some examples, a transmitting device may obtain channel access at a time 510 that is not aligned with an OFDM symbol boundary. If the gap or offset τ560 between CCA clear time 510 and the subsequent OFDM symbol boundary 520 of symbol k is less than CR preamble 540 length LK, the transmitting device may truncate CR preamble 540 by a certain number of samples 540a and transmit truncated CR preamble 540, with the last sample of CR preamble 540 aligned with OFDM symbol boundary 520 of symbol k. In the illustrated example, the truncated number of samples is the first LK- τ samples. The CR message 550 is then transmitted in the subsequent symbol k+1.

Fig. 6 illustrates an example 600 of an epoch in which an offset τ between the time of obtaining channel access and the boundary of a subsequent OFDM symbol may be longer than the preamble. Here, the transmitting device determines that the transmission medium is clear based on the CCA procedure at time 610. In the illustrated example, the offset τ660 between time 610 and the subsequent OFDM symbol boundary 620 of symbol k is greater than the CR preamble 640 length LK. In this example, the transmitting device may align the CR preamble 640 to begin at time 610 and then add padding samples 640a after the end of the CR preamble 640 until the OFDM symbol boundary 620. Various options may be used to populate sample 640a. For example, the transmitting device may use a copy of the first τ -LK samples of CR preamble 640 or a copy of the last τ -LK samples of CR message 650. Alternatively, the transmitting device may use a PN-like signal for padding samples. Further, the CR preamble 640 may be adapted such that it has a minimum duration, although OFDM symbol boundaries may intersect the CR preamble 640.

As described above, techniques for adaptive CR signal generation may include: the CR preamble is adapted to account for potential timing differences between the time at which channel access is obtained and the OFDM symbol boundary of the system in which the transmitting device operates. The CR signal may also be adapted based on occupancy of different partitions of the bandwidth used by the transmitting device. In particular, the bandwidth available to devices in the shared spectrum may be divided into equally spaced sub-bands to support channelization and fully utilize shared resources. For example, in the millimeter wave band (e.g., 60 GHz), the system bandwidth of 1GHz may be divided into two sub-bands, each 500 MHz. In another example, for the 3.5GHz band, the 80MHz system bandwidth may be divided into four sub-bands of 20MHz each. Each subband may have a different occupancy, including a different occupancy associated with the same device. Thus, a device may reserve channels for different subbands for different amounts of time and may transmit CR signals for various combinations of subbands.

For example, fig. 7 depicts an example configuration 700 for adaptive CR signal generation based on occupancy of different subbands within an available bandwidth. In the illustrated example, the channel is divided into four subbands 701a, 701b, 701c, and 701d. The transmitting device may occupy each subband at different times and for different durations. Thus, in some examples, a transmitting device may send a different and independent CR signal on each subband, where the CR signal indicates occupancy of the particular subband on which the CR signal was sent. In this configuration, the same CR preamble 710 is transmitted across each sub-band, and the payload of the CR message 715 includes information about occupancy of the sub-band on which the CR message 715 is transmitted. For example, a CR signal 702a transmitted on sub-band 701a will include a CR message payload 715 with a NAV value that indicates the occupancy of sub-band 701a by the transmitting device. Similarly, CR signal 702b transmitted on subband 701b will include CR message payload 715 with a NAV value that indicates the occupancy of subband 701b by the transmitting device, and so on for subbands 701c and 701d.

In other examples, the CR signal may include related occupancy information regarding multiple subbands or combinations of subbands. For example, the CR signal 730 transmitted on sub-band 701a may include the same CR preamble 720 across each sub-band, while also including a payload CR message 725 that includes occupancy information regarding the plurality of sub-bands. In some examples, CR message 725 may include a subband occupation bit map 725a indicating the subbands to which CR message 725 applies. In the illustrated example, CR signal 730 will include a subband occupation bit map 725a indicating that the occupation information contained therein applies to both subband 701a and subband 701d, while CR signal 735 will include a subband occupation bit map 725a indicating that the occupation information contained therein applies to both subband 701b and subband 701 c. The CR message 725 may also include a NAV value 725b indicating the occupancy of the sub-band indicated by the sub-band occupancy bit map 725a. As depicted in fig. 7, the occupancy of the individual subbands may vary over time. Thus, the transmitting device may send CR signals for different combinations of subbands. For example, the transmitting device may later send CR signal 740 indicating occupancy of sub-bands 701a and 701b and CR signal 745 indicating occupancy of sub-bands 701c and 701d.

The CR signal may also be adapted based on occupancy of different directional beams. For example, the transmitting device may transmit a beam or signal in a particular direction among a plurality of possible directions. The CR signal transmitted by the transmitting device may include occupancy information regarding one or more possible directions in which the beam was transmitted. Fig. 8 illustrates an example configuration 800 for adaptive CR signals based on occupancy of different beams. In the illustrated example, the transmitting device is a base station 105 that can transmit beams in one or more of three different directions 830a, 830b, and 830 c. Channels in direction 830a may be available while beam 830b will be reserved for a period of time Tnav for transmission to UE 115. Beam 830c may be blocked due to interference or other factors. In this example, the transmitting device 105 may send a CR signal including a CR preamble 810 and a CR message 820. The payload of the CR message 820 may indicate the beam occupancy and NAV 820a for beam 830b, and availability 820b for the other beams 830a and 830 c. Thus, the transmitting device may adaptively generate a CR signal to indicate reservation and availability of multiple beam directions.

Fig. 9 illustrates an example of a process flow 900 in a system supporting adaptive channel reservation signal techniques in accordance with aspects of the present disclosure. Process flow 900 may include base station 105 and UE 115, which may be examples of corresponding devices described with reference to fig. 1-2.

At 910, a transmitting device (such as base station 105) performs an LBT procedure to obtain channel access. In the present example, the transmitting device is base station 105, but the transmitting device may also be UE 115, and the operations described herein with respect to base station 105 may also be performed by UE 115. Similarly, the recipient device in the present example is a UE 115, but the recipient device may also be a base station 105.

At 920, the base station 105 generates a channel reservation signal based on obtaining channel access. The channel reservation signal may be based on the timing of obtaining channel access. For example, the waveform or number of samples included used in the channel reservation preamble may be based on an offset between the time at which channel access is obtained and symbol boundaries of the system in which base station 105 and UE 115 operate. Additionally or alternatively, the channel reservation signal may be based on other factors, such as occupancy of various subbands or beams available to the base station 105.

At 930, the base station 105 transmits the channel reservation preamble to the UE 115. The ue 115 determines 940 that the received signal is a channel reservation preamble and will then monitor 950 for a particular symbol for a subsequent channel reservation message based on the received channel reservation preamble. The UE 115 may then receive the channel reservation message transmitted by the base station 105 at 960.

At 970, ue 115 determines the channel occupancy based on the payload of the channel reservation message. In some examples, UE 115 may determine occupancy of different subbands or beam directions based on the channel reservation message.

Fig. 10 illustrates a flow chart diagram that describes a process 1000 for adaptive channel reservation signals in accordance with various aspects of the present disclosure. The operations of method 1000 may be implemented by a device, such as a base station or component thereof, or a UE or component thereof, as described with reference to fig. 1 and 2. For example, the operations of process 1000 may be performed by processor 240 or processor 280, alone or in combination with other components, as described herein. In some examples, the base station 105 or UE 115 may execute a set of codes for controlling the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 or UE 115 may use dedicated hardware to perform aspects of the functions described below.

At 1005, the base station 105 or UE 115 obtains channel access after a clear channel assessment operation. At 1010, the base station 105 or the UE 115 determines an offset between the boundary of the symbol and a particular time to gain channel access. At 1015, the base station 105 or UE 115 generates a channel reservation preamble based on the offset, as described above with reference to fig. 3, 4, 5, or 6. At 1020, the base station 105 or UE 115 transmits the channel reservation preamble.

Fig. 11 illustrates a flow chart diagram that describes a process 1100 for adaptive channel reservation signals in accordance with various aspects of the present disclosure. The operations of method 1100 may be implemented by a device, such as a base station or component thereof, or a UE or component thereof, as described with reference to fig. 1 and 2. For example, the operations of process 1100 may be performed by processor 240 or processor 280, alone or in combination with other components, as described herein. In some examples, the base station 105 or UE 115 may execute a set of codes for controlling the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 or UE 115 may use dedicated hardware to perform aspects of the functions described below.

At 1105, the base station 105 or the UE 115 obtains channel access to a communication channel after a clear channel assessment operation, wherein the communication channel includes a plurality of subbands. At 1110, the base station 105 or UE 115 generates at least one channel reservation signal based on the plurality of subbands, as described above with reference to fig. 7. At 1115, the base station 105 or the UE 115 transmits the at least one channel reservation signal.

Fig. 12 illustrates a flow chart that describes a process 1200 for adaptive channel reservation signals in accordance with various aspects of the present disclosure. The operations of method 1200 may be implemented by a device, such as a base station or component thereof, or a UE or component thereof, as described with reference to fig. 1 and 2. For example, the operations of process 1200 may be performed by processor 240 or processor 280, alone or in combination with other components, as described herein. In some examples, the base station 105 or UE 115 may execute a set of codes for controlling the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 or UE 115 may use dedicated hardware to perform aspects of the functions described below.

At 1205, the base station 105 or UE 115 obtains channel access after a clear channel assessment operation. At 1210, the base station 105 or the UE 115 generates at least one channel reservation signal based on the availability of beams in a plurality of possible directions, as described above with reference to fig. 8. At 1215, the base station 105 or UE 115 transmits the at least one channel reservation signal using one beam in a particular direction among the plurality of possible directions.

Fig. 13 illustrates a flow chart diagram that is an understanding of a process 1300 for adaptive channel reservation signals in accordance with various aspects of the present disclosure. The operations of method 1300 may be implemented by a device, such as a base station or component thereof, or a UE or component thereof, as described with reference to fig. 1 and 2. For example, the operations of process 1300 may be performed by processor 240 or processor 280, alone or in combination with other components, as described herein. In some examples, the base station 105 or UE 115 may execute a set of codes for controlling the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 or UE 115 may use dedicated hardware to perform aspects of the functions described below.

At 1305, the base station 105 or UE 115 receives a signal. At 1310, the base station 105 or the UE 115 determines that the signal includes a channel reservation preamble. At 1315, base station 105 or UE 115 monitors a symbol for a channel reservation message, where the symbol follows the end point of the channel reservation preamble. At 1320, the base station 105 or UE 115 identifies channel occupancy information based on the channel reservation message.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The functional blocks and modules in fig. 2 may include processors, electronics, hardware devices, electronic components, logic circuits, memories, software code, firmware code, etc., or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. The skilled artisan will also readily recognize that the order or combination of components, methods, or interactions described herein are merely examples and that components, methods, or interactions of the various aspects of the disclosure may be combined or performed in a manner other than those illustrated and described herein.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Computer readable storage media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Also, a connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL), then the coaxial cable, fiber optic cable, twisted pair, or DSL are included in the definition of medium. Disk (disk) and disc (disk) as used herein include Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disk) usually reproduce data magnetically, while discs (disk) reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

As used herein (including in the claims), the term "and/or" as used in the listing of two or more items means that any one of the listed items can be employed alone, or any combination of two or more listed items can be employed. For example, if a composition is described as comprising components A, B and/or C, the composition may comprise only a; only B; only C; a combination of A and B; a combination of a and C; a combination of B and C; or a combination of A, B and C. In addition, as used herein (including in the claims), the use of "or" in an item enumeration followed by "at least one of" indicates an disjunctive enumeration such that, for example, the enumeration of "at least one of A, B or C" represents any one of a or B or C or AB or AC or BC or ABC (i.e., a and B and C), or any combination thereof.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method, comprising:

obtaining channel access after a clear channel assessment, CCA, operation;

determining an offset between a boundary of a symbol and a particular time to obtain the channel access;

generating a CR preamble of a channel reservation CR signal based on the offset;

generating a CR message of the CR signal indicating availability of reservation and/or a plurality of beam directions, wherein generating the CR preamble includes dividing the CR preamble into a plurality of segments, each segment including a different waveform to identify the CR preamble and to identify a particular symbol of the CR message as expected; and

and transmitting the CR preamble and the CR message.

2. The method of claim 1, wherein the plurality of segments comprises a first segment having a fixed duration, a second segment having a variable duration, and a third segment having a fixed duration.

3. The method of claim 2, wherein the variable duration of the second segment is determined such that a total duration of the CR preamble is aligned with a duration of the offset.

4. The method of claim 2, wherein the generating the CR preamble further comprises: a different correlation type is applied to each segment.

5. The method of claim 4, wherein the generating the CR preamble further comprises: an autocorrelation type is applied to the first segment and a cross-correlation type is applied to the third segment.

6. The method of claim 1, wherein the CR preamble comprises a dual layer waveform configuration, and wherein the generating the CR preamble comprises: a short spreading sequence is used for a first layer of the CR preamble and a code cover sequence is used for a second layer of the CR preamble.

7. The method of claim 6, wherein the generating the CR preamble comprises: a cross product operation of the code coverage sequence indicated by a length L vector and the short spreading sequence indicated by a length K vector is performed.

8. The method of claim 7, wherein the offset has a duration that is shorter than a duration of the CR preamble.

9. The method as recited in claim 8, further comprising: the CR preamble is truncated such that the CR preamble has a start point aligned with the specific time and an end point aligned with the boundary of the symbol.

10. The method as recited in claim 8, further comprising: the end point of the CR preamble is aligned with the boundary of the next symbol after the symbol and a padding signal is added between the specific time and the start of the CR preamble.

11. The method of claim 7, wherein the offset has a duration that is longer than a duration of the CR preamble.

12. The method as recited in claim 11, further comprising: at least one padding sample is added in a gap between the end of the CR preamble and the boundary of the symbol.

13. The method of claim 12, wherein the at least one fill sample comprises at least one of: a copy of at least one sample from a beginning of the CR preamble, a copy of at least one sample from an end of a CR message scheduled for transmission in a next symbol after the symbol, or a pseudo noise signal.

14. An apparatus for wireless communication, comprising:

a processor;

a memory in electronic communication with the processor; and

instructions stored in the memory and when executed by the processor operable to cause the apparatus to:

Obtaining channel access after a clear channel assessment, CCA, operation;

and transmitting the CR preamble and the CR message.

15. The apparatus of claim 14, wherein the plurality of segments comprises a first segment having a fixed duration, a second segment having a variable duration, and a third segment having a fixed duration.

16. The apparatus of claim 15, wherein the variable duration of the second segment is determined such that a total duration of the CR preamble is aligned with a duration of the offset.

17. The apparatus as recited in claim 15, further comprising: a different correlation type is applied to each segment.

18. The apparatus as recited in claim 17, further comprising: an autocorrelation type is applied to the first segment and a cross-correlation type is applied to the third segment.

19. The apparatus of claim 14, wherein the CR preamble comprises a dual layer waveform configuration, and wherein the generating the CR preamble comprises: a short spreading sequence is used for a first layer of the CR preamble and a code cover sequence is used for a second layer of the CR preamble.

20. The apparatus of claim 19, wherein the generating the CR preamble comprises: a cross product operation of the code coverage sequence indicated by a length L vector and the short spreading sequence indicated by a length K vector is performed.

21. The apparatus of claim 20, wherein the offset has a duration that is shorter than a duration of the CR preamble.

22. The apparatus as recited in claim 21, further comprising: the CR preamble is truncated such that the CR preamble has a start point aligned with the specific time and an end point aligned with the boundary of the symbol.

23. The apparatus as recited in claim 21, further comprising: the end point of the CR preamble is aligned with the boundary of the next symbol after the symbol and a padding signal is added between the specific time and the start of the CR preamble.

24. The apparatus of claim 20, wherein the offset has a duration that is longer than a duration of the CR preamble.

25. The apparatus as recited in claim 24, further comprising: at least one padding sample is added in a gap between the end of the CR preamble and the boundary of the symbol.

26. The apparatus of claim 25, wherein the at least one fill sample comprises at least one of: a copy of at least one sample from a beginning of the CR preamble, a copy of at least one sample from an end of a CR message scheduled for transmission in a next symbol after the symbol, or a pseudo noise signal.

27. A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable to:

obtaining channel access after a clear channel assessment, CCA, operation;

And transmitting the CR preamble and the CR message.

28. An apparatus for wireless communication, comprising:

means for obtaining channel access after a clear channel assessment, CCA, operation;

means for determining an offset between a boundary of a symbol and a particular time at which the channel access is obtained;

means for generating a CR preamble of a channel reservation CR signal based on the offset;

means for generating a CR message of the CR signal indicating the availability of reserved and/or multiple beam directions, wherein the means for generating the CR preamble comprises means for dividing the CR preamble into a plurality of segments, each segment comprising a different waveform to identify the CR preamble and to identify a particular symbol of the CR message as expected; and

means for transmitting the CR preamble and the CR message.